Bumblebee Math

The February 2012 National Geographic Magazine, page 26, describes an experiment designed to test how efficiently bumblebees navigate between flowers. Six artificial nectar sources were setup near a nest box. And individual foraging behavior was monitored. Here’s what they found:

The flight of the bumblebee-even when not set to music-may seem frenetic and random as the workers forage for pollen and nectar to carry home. But researchers at Queen Mary, University of London discovered there’s choreography in the flower bed. Each bee has a brain the size of a grass seed, but the insects are able to harvest efficiently by solving one of math’s great puzzles: the traveling salesman problem.

The challenge is to find the shortest way to visit each flower once before returning to the nest. Computers must resort to laborious calculations, measuring each possible route. The bees studied, Bombus terrestris, and perhaps other species use spatial memory, rapidly refining routes through trial and error. (Hint: Moving to the next nearest flower isn’t the answer.) Scientists know why the bees do it – ­flying is exhausting. Now they’re trying to figure out how the insects do it. Learning what dictates their decisions could yield insights that improve our transportation and communication networks. To the bees, it’s just a matter of good orchestration. -Gretchen Parker

I hate to admit it, but I figured bee foraging was a more random process. Maybe at best, bees would fly to the nearest source and then work the next nearest source in a particular direction. That’s how the bus I drive is dispatched.

But that’s inefficient, especially when more than one bus is involved. It’s not uncommon for two buses to pass each other to finish that last leg shown in the longest route diagram above. And they end up where the other was! 😉